Research suggests that youth do not use condoms because they trust their partner. This article describes the Trusted Partner regional behavior change communication campaign and uses data from Lesotho, Mozambique, Uganda, and Zambia to evaluate the impact of the campaign. Cross-sectional surveys of youth aged 15 to 24 were conducted in each country before and after the campaign. The surveys measured elements related to trust and condom use with a regular partner. Multivariate logistic regressions were used to investigate the determinants of condom use and whether exposure to the campaign was associated with condom use. The evaluation of the campaign showed mixed results. The percent of youth recalling the campaign varied among countries: 32% in urban Lesotho, 54% in urban Mozambique, 16% in Uganda, and 39% in urban Zambia. In all 4 countries, sexual caution with a partner had a positive relationship with condom use. However, exposure to the campaign was only associated with condom use in Mozambique. These results from Mozambique indicate that more intense exposure may be necessary to achieve impact. Regional campaigns appear to be a cost-effective way to reach large numbers of youth, but more detailed measures of exposure should be pursued to improve program evaluations.<\/p>\n